I will present an overview of recent projects where we have proposed new approaches to the experimental study of active matter. In particular, I will present a new algorithm for the measurement of microscopic force fields and a deep-learning approach to the tracking of microscopic particles.

The first symposium on the topic of Nanophotonics brings together researchers from physics and chemistry departments in Gothenburg to present their work and share ideas.

Organised by Dr. R. Verre from the Bionanophotonic group at Chalmers University of Technology seven different groups will be present among which F. Schmidt will represent our Softmatter division of Gothenburg University.

The symposium will take place on the 26th of March 2019 at Kollektorn in MC2, Chalmers Campus. Everybody is welcome to attend!

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

I will first give a brief overview of optical trapping and optical manipulation — the invention that has earned Arthur Ashkin the 2019 Nobel Prize in Physics. Then, I will focus on some recent applications where we have used optical tweezers to characterise critical Casimir forces and to manipulate active matter. Finally, I will present a new approach to the calibration of optical forces that we have recently developed in collaboration with UNAM.

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

Active matter, consisting of self-propelled units locally injecting energy into the system, opens new horizons for the creation of functional soft materials with designable properties. Experiencing a constant energy input, allows active matter to self-assemble into phases with a complex architecture and functionality such as living clusters which dynamically form, reshape and break-up but would be forbidden in equilibrium material by the entropy maximization (or free energy minimization) principle. The challenge to control this active self-assembly has evoked widespread efforts typically hinging on an engineering of the properties of individual motile constituents. Here, we provide a different route, where activity occurs as an emergent phenomenon only when individual building blocks bind together, in a way which we control by laser light. Using experiments and simulations of two species of immotile microspheres, we exemplify this route by creating active molecules featuring a complex array of behaviors, becoming migrators, spinners and rotators. The possibility to control the dynamics of active self-assembly via light-controllable nonreciprocal interactions will inspire new approaches to understand living matter and to design active materials.

Albanova, Stockholm’s center for Physics, Astronomy and Biotechnology cordially organizes a panel discussion about this year’s Nobel Prize in Physics, followed by a social gathering with drinks and snacks.